1. Field of the Invention
The invention relates to a procedure for injecting fuel in particular into the combustion chamber of internal combustion engines via a swirl injection nozzle with axially movable valve needle, wherein the pressurized supplied fuel is made to rotate around the valve needle in an annular swirl chamber arranged in front of the outlet nozzle. The invention also relates to an injection nozzle suitable for executing the procedure.
2. The Prior Art
Numerous procedures and devices are already known for injecting fuel directly into the combustion chamber of both diesel and Otto engines. The fuel is injected into the combustion chamber of the engine and atomized via a pump-nozzle system or a pump-line-nozzle system (common-rail system) during compression. The injection process can also take place in several phases, so-called, pre- and main injection. One significant feature shared by these injection systems is that atomization takes place from the rest phase of the liquid. In a period measuring in the milliseconds, the potential energy is used for conversion into kinetic energy (fuel velocity), and the low quantity of fuel is atomized to the nozzle outlet opening.
DE-OS 24 60 111 already discloses a generic injection nozzle for injecting a liquid in a chamber subjected to pressure fluctuations during a low-pressure phase.
The supplied fuel enters an annular chamber arranged around the nozzle needle guide, and from the latter via tangential inflow openings at the end of the nozzle needle guide into an annular swirl chamber, which is arranged around the nozzle needle. An annular flow is built up inside the swirl chamber, and stored therein. Given a higher volume of the swirl chamber, the rotational effect can be amplified even further by arranging at least one reflux opening in the swirl chamber, which preferably connects to the swirl chamber in a roughly tangential manner, and is located at the top end of the annular chamber in the nozzle needle guide. The tangential inflow opening and tangential reflux opening are arranged opposite relative to the direction of flow. As indicated in this publication, the fuel is to be intermediately stored rotating in the swirl chamber. Intermediate storage is only on hand if the reflux opening is also closed at least with the nozzle outlet opening closed. As a consequence, the rotational velocity decreases during intermediate storage. During the ejection process, the flow of fuel divides into two partial streams with the reflux opening open, wherein the upwardly directed partial current generates swirls in the direction of the reflux opening that have a negative effect on the atomization quality.
Also known is an electromagnetic fuel injection valve for internal combustion engines (U.S. Pat. No. 4,179,069), which is intended in particular for the injection of fuel into the suction pipe of a vehicle motor. The fuel is injected via a swirl injection nozzle with axially moveable valve needle, wherein the pressurized fuel is made to rotate around the valve needle in an annular swirl chamber arranged directly in front of the outlet nozzle, and the fuel is introduced into the swirl chamber at its largest radius through a fuel inlet line that generates the peripheral velocity component. The fuel flow is removed where the radius of the swirl chamber is narrowest, concentrically to the valve needle. During the injection phase, removal of the fuel from the swirl chamber is interrupted.
A procedure for injecting fuel via a swirl injection nozzle with axially moveable valve needle is also known from U.S. Pat. No. 4,805,837. An annular swirl chamber is arranged directly in front of the outlet opening of the nozzle. The fuel is introduced into the swirl chamber at its largest radius, and removed concentrically to the valve needle where the radius of the swirl chamber is narrowest with the outlet opening closed. During the injection phase, removal of the fuel is interrupted.
The disadvantage to the known injection procedures mentioned above is generally that the injection quantity for achieving an optimal injection progression cannot be varied sufficiently, and the achievable atomization quality does not reflect the set high requirements.